Rubber compositions containing octadecane nitrile



Patented Mar. 9, 1948 UNITED STATES PATENT orrica RUBBER COMPOSITIONSCONTAINING GCTADECANE mama John H. Kelly, Jiz, Oak Park, Ill., assignorto Dryden Rubber Company, Chicago, 111., a corporation of Illinois NoDrawing. Application May 27, 1943,

Serial No. 488,694

3 Claims. (Cl. 260-5) 1 The invention relates to oil resistant rubbercompositions and to methods of making the same.

One object of the invention is to provide any oil resistant reclaimedrubber composition.

Another object is to provide an oil resistant extender for syntheticrubber-like copolymers of butadiene acrylonitrile and for the variousother oil resistant rubber polymers derived from the polymerization ofdienes in general.

Other objects of the invention will become apsteam devulcanization.These reclaims are used as a base for building up oil resistingcompositions. When suitably compounded with octadecane nitrile, sulfurand a dior tri-substituted aryl guanidine, and preferably magnesiumoxide or other alkaline earth oxide, these compositions aftervulcanization reveal unusually good oil resistance, and in addition arecharacterized by excellent tensiles, elongation and elasticity inthemselves. If these compositions are selves as inexpensive oilresistant compounds, greater utility is found as extenders for syntheticrubber. After vulcanization, essentially similar oil resistantproperties are found. It is contemplated that these extenders can beused with the various rubber-like polymers such as polychloroprene,butyl rubbers and the like..

,However, it has given particularly satisfactory results with thebutadiene acrylonitrile copolymers.

c In building up these oil resistant compositions the proportions of thevarious ingredients vary.

' Preferably the sulfur constituent of the comblended with oil resistingsynthetic rubber-like Y products such as the butadiene acrylonitrilecopolymers, it is found they act as very good and inexpensive oilresistant extenders of the synthetic copolymer. As will be revealed, theuse of these extenders does not lower the inherent oil resistance ofthese copolymers to any marked extent.

Another embodiment of this invention consists I of utilizing cruderubber instead of reclaim. If

compounded as with the reclaims by suitable amounts of the alkylnitrile, alkaline earth oxide, sulfur and a substituted guanidine, thecrude rubber composition has also proved utilizable with the syntheticcopolymers. Oil resistant properties are again evident in thecompositions as revealed in the examples submitted hereafter.

In my invention, I prefer to use a reclaimed rubber. It is considerablymore economical and confers better processing characteristics upon thebutadiene acrylonitrile or other copolymers. Milling, calendering orextrusion characteristics are greatly improved and the usual processingdimculties minimized.

While these compounds may be used by thempound is kept in excess. of 20%by weight on the rubber hydrocarbon itself or else on the rubberhydrocarbon value of the reclaim. The substituted aryl guanidine ispreferably present in the ratio of three to five molecular equivalentsby weight on the sulfur. Suitable proportions of the octadecane nitrileare usually from 15% to or more of the hydrocarbon value of theextender.

As an example, utilizing a low grade molded mechanical reclaimcontaining 40% rubber hydrocarbon value and derived from molded scrap bythe heater process and which possesses these physical characteristicsafter the 5% sulfur, cure,

Hardness Tensile 1 39,5 Elongation percent 260 Ash I do 21.89 Acetoneextract do 16.46 Rubber hydrocarbon content do 40.12

the following is submitted;

. EXAMPLE I A reclaimed rubber composition suitable as an oil resistantcomposition by itself or else as an extender for butadiene acrylonitrilecopolymers was compounded as follows, using the molded black scrapheater process reclaim as a base.

Reclaim extender A Molded mechanical reclaim 25.0000

Magnesium oxide .4375 Triphenyl guanidine 5.2500 Sulfur 2.3125Antioxidant .7500 Octadecane nitrile -i- 1.8750

3 a butadiene acrylonitrile copolymer to give the following composition:

Butadiene acrylonitrile copolymer synthetic The above product, l resscured in slabs 2" x 8" at 330 for 45 minutes, gave excellentollresistance. Three hours immersion in h the range of this invention.This reclaim, vulkerosene at 70 F. evidenced less than 2 /270 canizedminutes at 287 F. after the usual 5% r se in. w ht and'l ss than i cr insulfur addition possesses the following physical volume.characteristics:

Exmnr II 20 Hardness 40 In order to determine the influence of ordi-Tensile 718 nary reclaims as a factor in creating oil resistanceElongation per cent 395 with the reclaim extender "A" as shown in Ex-Specific gravity (corrected) 1.18 ample I, and to compare oil resistanceof an Acetone extract per cent 9.21 untreated reclaim versus thiscompounded re- Ash an 1 ,00 claim extender, the following examples aresub- Rubber hydrocarbon value by difference mitted illustrating theprocedures involved. In per cent 58.16 these examples the reclaims, boththe uncompounded reclaim of the extender and the reclaim 3o C mpoundinin a dan e wit t prin ip selected for comparison, were first sheeted outof establishing at least a minimum of 20% sulfur on a mill and thenadded to the butadiene acryon the hydrocar on V ue of t reclaim, thelonitrile copolymer on the mixing mill, followed llowing comp i wProduced: by the compounding ingredients. This procedure I gave a moreuniform and advantageous compari- Reclaim extender B son on each batch,and in addition illustrates the whole tire reclaim 100 basic advantageof the invention. Triphenyl 81mm dine M 30.9

Sulfur 1 13.8 "A" 3" Magnesium oxide 2.4 40 Antioxidant 4.5

Octade a e nitrile 1. tilomil 'tf'ii.i ifiiiiffffiffffifififf'2:88 1 255,333 disumde 91% 9% This extender was refined and slabbed oil. atSemi-reinforcing black 30.00 moo the usual refining gauge of .005" to.007" and g fijmg gfiflf fffif 3% 83 then mixed with a butadieneacrylonitrile cogfilr t efi mcg l nechanical rec aim 7 {2 28 polymer asshown below. 8 0.40 Light calcined magnesium Oxide 1.10 Butadieneacrylonitrile copolymer synthetic o'eifimnm. 1 23 rubbm' 100 Soft coaltar (140 F. M. P.) 3 Zinc oxide 10 In mixing, the ingredients ofcompound "3 were Sulfur 1 added to the butadiene acrylonitrile copolymerBenzothiezyl disulfide 1 synthetic rubber ingredients, including theocta- 'Irimethyl dihvdroquinoline 1 decane nitrile, which was added lastas in ordl- Channel black '1 nary mixing procedures involving theplasticizers. Reclaim extender 1501! Press cured slabs 2" x a", 45minutes at 330- F. Octadecane nitrile 0 resultedm the followingcomparison' After vulcanizing the 2" x 8" slabs 45 min. at 6 330 F. theresistance to hot kerosene is easily Percent change witnessed in thefollowing comparison: gg' Tensile Weight Volume Percent change gwonHard- Elon- Recovness Tensile gatlon cry no'r KEBOSENE IMMERBION,48norms a'r 100 0. 65 weight mum gn mnu 55' 950 280 1035'53::::::::::::::::: t? 323 313 21 32? 33 55 w 250 m6 IMMERSION'Q HelmsAT ROOM 70 The resistance to various other solvent com- TEM E Tpositions is excellent.

"A" 40 e10 750 +3 ,+5o.s LE IV "8" 730 250 -2 6 In illustrating the useof ordinary crude rubber 7o compounded to give a similar hydrocarbonvalue 4 The PPF fuel admixture consisted of a mixture of octane gasoline60%, benzol 5%, toluol 20%, and xylol 15%.

It will be observed the extender is markedly superior to ordinaryreclaimed rubber in butadiene acrylonitrile copolymer compounds. Inaddition, variationof the mixing procedure to produce the extender insitu instead of producing the extender composition first and thenblending into the polymer does not markedly affect the oil resistance.

Exmu: III

The use of a standard whole tire alkali process reclaim is given belowas an example illustrating acsa aaa content, 40%, as existing in thereclaim constituent of reclaim extender Min Example I, the following issubmitted.

The V." press cured slabs. 45 minutes at 831, gave the followingresults:

P t 11 Crude rubber ewtenderC" Hard- Tensile E1 Recovmm 0 me 11688 gacry No. 1 smoked sheet 100.00 Weight Vdume Thermatomic soft black 145.00Zinc oxide 5.00 gggg i g'gggg 68 300 112 st acid 2,00 at 1015 80 1,210130 100 -s.0 -a2 Triphenyl guanidine 50.00 :322:31; Light magnesiumoxide 4.00 fgng g 76 1,370 250 112 [1B J t ti it 11 2330 glrglfd M048 .1m mc eca'ne n r e peratg e 05 1,120 150 112 44.5 +0.9 As shown by theabove example the rubber is 28.7% by weight of the composition, and theEXAMPLE VI sulfur 1 2 y W i ht of the rubber. The influence of high andlow plasticizer con- Milling Was followed as 1 accepted Procedures tentis shown in the following two compounds n n t the art, and the compoundslflbbed which further illustrate the utility of the reac- In comparingthe use of crude rubber exnon: 1 tenders against a typical reclaimextender, the following is given:

. u n u n B (11 l I 1 b l' A B dihtdfi$t$193.Yfffffifffffiffff? 33.33 1%zgfis z i 01101000 1 23 i 53 gtictigdiiiiitfiiftiifffffi ffiifififff 2:0"2183 a discussant-11111111111 1 g ztt'n'fmf fii 131% 33% igg gg ggggfleg 33% 33-3 Efififi 5% ;;g Octadecenenitrile- .::IIIIIII: 30100 50:00assesses m m 86 U I! Octsdecanenitrile 50.00 50.00 slabs vulcanized 45minutes at 331 F. give the following results:

The above compositions were press cured for 35 v 45 minutes at 331 F.,slabs, and results of Ham Elm Ream Pemmchange tests are shown in thefollowing table: ness 9 gation ery Weight Volume I tch Hard- TensflElon- Recovemen ange i 'i 61 1,140 240 106 ness 8 gation cry 3" 48 950310 106 Weight Volume s11: 00%"... 10 1,350 200 100 -1.4 -0.7 1 55 212001 1 030 200 100 12 3 10 8 00am;

"B" 47 910 330 100 45 48]]0111'3at212" fig F. "131 58 1,050 270 106 -0.0s.0 "A" 00- 110 220 100 -1.0 +0.21 atfitfibta' 60 m 106 1 r 5 860 240 10-4.4 -4-1 F. "B" 55 000 200 100 -4.1 -s.0 48 hours etc- 100 octane fuel1 "A" 00 850 250 100 +14.8 +zs.1 60 a, 50 1 0 250 10 +3.2 6 #10 3??? 070200 10s +2.0 +4.0

Aromatic iuel bland fuel The value of crude rubber is strikinglyillusmg- :535 103 trated in these examples, and it is obvious the temp au e somewhat higher absorption of the aromatic fuel 55 B 580 m 103 +27blend favorably compares with many polymerized 2 h1 b tad1 compounds Inexamining the resistance of the various extenders, it will be noticedthat the crude rubber EXAMPLE V extenders while evidencing fairly goodresistance 1 00 against hot petroleum derivatives, notably kero- As anexample illustrating the use of other sene, nevertheless are inferior inbehavior to the plasticizers than octadecane nitrile in the butatreatedreclaims when blended with butadiene diene aerylonitrilecopolymer-extender blends, acrylonitrile copolvmer synthetic rubber,notably the following is submitted: against the aromatic fuel basemixture consist- 65 ing of octane gasoline, 15% xylol. 20% Butadieneacrylonitrile copolymer syntoluol, and 5% benzol. However, it isapparent thetic rubber 100.00 from the above examples that crude rubbercom- Soft coal tar (140 F. M. P.) 3.00 positions may be used in myinvention and give Zinc oxide 10.00 I advantageous results when mixedand com- Sulfur 1.00 pounded as illustrated. Benzothiazyl disulfide 1.00While there have been shown and described Trimethyl dihydroquinoline -11.00 certain embodiments of the invention, it is Semi-reinforcing black125.00 understood it is capable of many modifications. Reclaim extender"A 50.00 As an example, the use of diphenyl guanidine Dibutyl phthalate40.00 can be substituted molecular equivalent for amass 7 molecularequivalent of the triphenyl guanidine without appreciably. affecting theresults. Similarly other substituted guanidines such as diotolylguanidine and others have been successfully utilized. In addition thesulfur and substituted guanidines can be fused or melted together toform admixtures or complexes as shown in my co-pending applicationSerial No. 415,776

and after milling into the reclaims as described,

offer essentially similar results.

In contrast to the behavior of octadecane nitrile in ordinarycompounding technique as practised with the Hycar butadieneacrylonitrile compositions, the additions of amounts exceeding 25% byweight on the polymer have no adverse efiect on the cure whenever thereclaim or crude rubber extenders are also incorporated into thebutadiene acrylonitrile copolymer synthetic rubber. As is well known,octadecane nitrile in excess of 25% of the butadiene acrylonitrilecopolymer weight, such polymer containing the usual 1% to 1.5% sulfurwill not vulcanize thoroughly as the cure is then definitely retarded.In the presence of these extenders no such adverse efiect is noted sofar as the oil resistance is concerned.

EXAMPLE VII 48 hour test 100 octane aviation fuel Hard- Elon- Recov-Hess Tensile gmon ery Weight Volume Reclaim extender "A" 55 320 170 107+1.01 +1.04 Crude rubber eXtenderC"- 75 790 190 118 +0.4 +1.3

While there have been shown and described certain embodiments of theinvention, it is to be understood that it is capable of manymodifications. Changes, therefore, may be made without departing fromthe spirit and scope of the invention as described in the appendedclaims, in which it is the intention to claim all novelty inherent inthe invention as broadly as possible, in view of the prior art.

Throughout this specification the amounts of materials given in theexamples are parts by weight unless otherwise noted. The tensilestrengths are in pounds per square inch, the hardness is shore hardness,and the elongation is in percent.

I claim:

1. The composition of claim 2 in which the rubber and sulfur arecombined by vulcanization.

2. A composition comprising reclaimed vulcanized natural rubber,octadecane nitrile, sulfur, triphenyl guanidine, and abutadiene-acrylonitrile synthetic rubber, the sulfur being present in atleast 20% and not above 23.7% by weight of the natural rubberhydrocarbon, the triphenyl guanidine being present in from three to fivemolecule equivalents by weight on the sulfur, the octadecane nitrilebeing present in from 15% to on the hydrocarbon value of the naturalrubber, and the natural rubber being present in not less than 28.7% byweight of the composition excluding the synthetic rubber.

3. A composition of matter particularly adapted for use as an extenderfor oil resistant butadiene acrylonitrile synthetic rubber, saidcomposition comprising natural rubber, octadecanenitrile, sulfur, and anaryl guanidine selected from the group consisting-of diphenyl guanidine,triphenyl guanidine and diorthotolyl guanidine, the sulfur being presentin at least 20% and not more than 23.7% by weight of the rubber, thearyl guanidine being present in between three to five moleculeequivalents of the sulfur, the octadecanenitrile being present in from15% to 50% of the hydrocarbon value of the rubber, and the rubber beingpresent in not less than 28.7% by weight of the composition.

JOHN H. KELLY, Ja.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,080,910 Coons May 18, 19372,088,920 Pickett Aug. 3, 1937 2,271,125 Juve Jan. 27, 1942 2,287,773Bacon, et al June 30, 1942 2,319,634 Sauser May 18, 1943 2,381,248Bascom Aug. 7, 1945

